Neuromodulatory inputs to early sensory processing areas, such as acetylcholine, noradrenaline, serotonin and dopamine, are thought to support a number of functions relating attention, alert, reward and emotional states. Neuromodulatory inputs regulate the states of sensory and cortical networks, change local computations and affect the dynamics of these networks. Among early sensory processing areas, because of the strong correlations between sensory inputs, neural activity and perception, the transformation of sensory perception by neuromodulatory inputs is directly measurable in the olfactory bulb (OB) of rodents. A crucial function of the OB is to integrate afferent information from the sensory neurons in concert with descending cortical and neuromodulatory inputs from central structures such as the piriform cortex, basal forebrain and brain stem. Accumulating evidence indicates that olfactory discrimination is at least partially mediated by processes in the OB and that cholinergic as well as noradrenergic centrifugal inputs to the OB modulate perceptual discrimination. The present proposal uses multi-electrode recordings in behaving rats to further elucidate the contribution of cholinergic and noradrenergic inputs to the OB for olfactory perception and learning. Neural activity in the locus coeruleus and horizontal limb of the diagonal band of Boca will be recorded in rats performing one of three different olfactory tasks. We hypothesize that cholinergic inputs will be involved in shaping olfactory representations and comparisons of stimuli to those previously encoded whereas noradrenergic inputs will be involved in the formation and maintenance of short memoires as well as in the regulation of signal-to noise ratio. PUBLIC HEALTH RELEVANCE: Neuromodulatory inputs to primary sensory cortex modulate sensory perception and learning. Disruption of these processes leads to impairments in the detection, discrimination and learning of sensory inputs. The proposed work will have significance for our understanding of how neuromodulatory inputs are involved in sensory processing and memory formation.